CT-angiography of the aorta in patients with Marfan disease - High-pitch MDCT at different levels of tube voltage combined with Sinogram Affirmed Iterative Reconstruction.

OBJECTIVES: Aim of the study was the comparison of high-pitch dual-source CTA of the aorta acquired with different tube currents and methods of image reconstruction in patients with Marfan Disease (MFS). BACKGROUND: Patients with MFS receive repeatedly CT examinations of the entire aorta what leads to high cumulative lifetime radiation doses. Routine clinical use of low-kV-protocols in combination with iterative reconstruction for imaging of the aorta is still limited although this approach may be of great benefit for patients in need of serial follow-up scans. METHODS: 106 patients with MFS received CTA of the entire aorta in a 2nd generation dual-source Flash-CT at 120, 100 or 80 kV. 120 kV images were reconstructed with FBP, low-kV images with an IR algorithm (SAFIRE) at different noise reduction levels. CTDIvol, DLP and effective dose were analyzed. Quantitative image analysis included comparison of SNR, CNR and Noise levels. For qualitative analysis, two blinded readers assessed noise, contour delineation, contrast, overall image quality and diagnostic confidence. RESULTS: Effective dose was 9.4 (±1.5) mSv for 120 kV, 4.2 (±1.1) mSv for 100 kV and 1.9 (±0.42) mSv for 80 kV. 100 kV images showed the highest SNR and CNR values, followed by 80 kV and 120 kV. Qualitative image analysis showed the lowest scores for all evaluated aspects at 80 kV. Overall image quality and diagnostic confidence was excellent at all kV strengths. CONCLUSIONS: In MFS patients low-kV CT protocols with IR allow for CTA of the entire aorta in excellent image quality and diagnostic confidence with a dose reduction of up to 80% compared to 120 kV. For baseline CT, we recommend 100 kV, for follow-up CT scans 80 kV as tube voltage.

CT follow-up in patients with neuroendocrine tumors (NETs): combined radiation and contrast dose reduction.

Background Frequent computed tomography (CT) follow-ups involve significant radiation related risks for patients with low-grade neuroendocrine tumors (NETs). Contrast agent (CA) application is essential for diagnostic evidence and has additional risks especially in patients with limited renal function. Purpose To investigate if a combination of dose and contrast agent (CA) reduction affects image quality and diagnostic evidence in neuroendocrine tumor (NET) patients. Material and Methods A total of 51 NET patients were enrolled in the study and 153 CT scans were analyzed. Patients underwent a baseline CT scan (A = 120 kVp, filtered back projection [FBP]) and two follow-up CTs (B = 120 kVp, adaptive statistical iterative reconstruction [ASIR] 40%; C1 = 100 kVp, ASIR 40%; C2 = 100 kVp, ASIR 60%; the latter two protocols were applied with a 30% reduction in CA volume). We evaluated image quality and applied dose. Results In C1/2, the combination of low kV (100 kVp) with ASIR 40%/60% reduced the mean applied dose significantly by 28% compared to B and by 57% compared to A. Signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR) of tumor to liver/muscle were significantly increased by using C1/2 compared to B and A. With respect to subjective image quality, a slight loss of diagnostic confidence in C1 could be counterbalanced by the higher ASIR blending in C2. Conclusion Combined dose reduction techniques can be used to reduce radiation dose and CA volume without sacrificing image quality and diagnostic confidence in staging CT of NET patients.

Percutaneous computer tomography-guided ethanol sympathicolysis for the treatment of resistant arterial hypertension.

PURPOSE: As an alternative to catheter-based radiofrequency (RF) ablation, renal sympathicolysis can also be achieved by image-guided percutaneous injection of ethanol around the renal artery. MATERIALS AND METHODS: We report the case of a 50-year-old man with refractory hypertension and end-stage renal failure of unclear etiology who was treated with computed tomography-guided percutaneous periarterial ethanol sympathicolysis. RESULTS: The procedure was painless. The patient's BP decreased within 6 days from a baseline value of 172/84 mm Hg (1 week before treatment) to a sustained decreased value of 143/70 mm Hg 1 month after intervention, i.e., a decrease by 29/14 mm Hg. The patient's hypertension-related headache resolved. CONCLUSION: Image-guided periarterial ethanol injection for renal sympathetic denervation in a patient with drug-resistant hypertension is feasible. We provide a detailed description of this new interventional procedure and discuss its potential advantages compared with catheter-based RF ablation.

Plasma levels following application of paclitaxel-coated balloon catheters in patients with stenotic or occluded femoropopliteal arteries.

PURPOSE: Paclitaxel-coated balloon catheters inhibit restenosis after coronary and peripheral angioplasty (PCI,PTA). The aim of this study was to investigate paclitaxel plasma levels and laboratory parameters following PTA with paclitaxel-coated balloons (PCB) in peripheral arteries. MATERIALS AND METHODS: This single treatment arm, multicenter study included 14 patients with Rutherford stage 1 - 5 with occlusions of up to 5 cm or ≥ 70 % diameter stenosis of the superficial femoral or popliteal arteries (SFA, PA). PTA was performed using up to three PCB catheters. The paclitaxel plasma levels and safety laboratory parameters were determined by collecting blood samples pre-intervention, immediately post-intervention, at 0.5, 1, 2, 4, 8, 24 hours and 1 and 4 weeks post-intervention (p. i.). Vital signs were monitored to assess clinical safety. RESULTS: PTA was performed successfully in all patients. Paclitaxel plasma levels were always below a level and duration known to cause systemic side effects. A mean peak paclitaxel plasma level (40 ng/ml) was reached immediately p. i. and decreased rapidly below detectable levels in more than half of the patients already 2 hours p. i. The paclitaxel plasma concentrations returned to values below detectable levels at 24 hours p. i. in all patients. Laboratory parameters and vital signs did not give any reason for safety concerns. No adverse events associated with balloon coating were observed. CONCLUSION: The results of 14 patients with peripheral arterial occlusive disease show no systemic bioavailability of paclitaxel > 24 hours after PTA with one or more PCB catheters, indicating that the PCB catheter is safe with regard to possible systemic effects.

Comparison of different cardiac MRI sequences at 1.5 T/3.0 T with respect to signal-to-noise and contrast-to-noise ratios - initial experience.

PURPOSE: To compare image quality, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) of different MRI sequences for cardiac imaging at 1.5 T and 3.0 T in volunteers. MATERIAL AND METHODS: 10 volunteers (5 male, 5 female) with a mean age of 33 years (+/- 8) without any history of cardiac diseases were examined on a GE Signa 3.0 T and a GE Signa 1.5 T TwinSpeed Excite (GE Medical Systems, Milwaukee, WI, USA) scanner using a 4-element phased array surface coil (same design) on the same day. For tissue characterization ECG gated Fast Spinecho (FSE) T (1)- (Double IR), T (1)-STIR (Triple IR) and T (2)-weighted sequences in transverse orientation were used. For functional analysis a steady state free precession (SSFP - FIESTA) sequence was performed in the 4-chamber, 2-chamber long axis and short axis view. The flip angle used for the SSFP sequence at 3.0 T was reduced from 45 degrees to 30 degrees to keep short TR times while staying within the pre-defined SAR limitations. All other sequence parameters were kept constant. RESULTS: All acquisitions could successfully be completed for the 10 volunteers. The mean SNR 3.0 T compared to 1.5 T was remarkably increased (p < 0.05) for the T (2) - (160 % SNR increase), the STIR-T (1)- (123 %) and the T (1)- (91 %) weighted FSE. Similar results were found comparing CNR at 3.0 T and 1.5 T. The mean SNR achieved using the SSFP sequences was more than doubled by 3.0 T (150 %), but did not have any significant effect on the CNR. The image quality at 3.0 T did not appear to be improved, and was considered to be significantly worse when using SSFP sequences. Artefacts like shading in the area of the right ventricle (RV) were found to be more present at 3.0 T using FSE sequences. After a localized shim had been performed in 5/10 volunteers at the infero-lateral wall of the left ventricle (LV) with the SSFP sequences at 3.0 T no significant increase in artefacts could be detected. CONCLUSIONS: In all cardiac FSE sequences, SNR and CNR at 3.0 T were found to be increased compared to 1.5 T without any major changes of the sequence parameters. The adjusted SSFP sequences fulfilled the expected increase in SNR at 3.0 T but showed no increase in CNR. On the contrary, the overall image quality did not change or was even found to be significantly lower for the SSFP and the FSE sequences at the free wall of the RV. Nevertheless, the results are encouraging for the use of 3.0 T for cardiac tissue characterization and new applications with progressing use of parallel imaging.